Support for enums and static variables

Assumptions:

1. There are no circular dependencies in initialization of static variables.
2. Enums are immutable.
3. The initialization is done before the main method is executed.

Current errors in the pipeline:

• There is a sanity check test to force all interprocedural arcs to be either input xor output. The newly introduced connection between static trees and formal-in trees breaks this assumption.

Missing elements:

• A connection from the usage to the initialization, and in the case of objects and enum constants, their corresponding constructor.

Theory

Enums:

• They are classes with a limited number of instances, specified in the source code.
• They are final (can't be extended) and they themselves extend from Enum.
• Despite the previous point, the explicit constructor call super() is illegal, and will result in a compilation error.
• An enum's instances are called its constants. They are public static final variables of the enum's type.
• If no parenthesis are specified next to the constant, the default constructor is used. Otherwise, the constructor that matches the arguments is used.
• Enums are initialized when the enum class file is loaded into the JVM (the first time that it is referenced in the execution of a program). More details.

Design

1. Each class and enum is represented as a single node in the SDG. In its object tree, its static fields are represented. In the case of enums, the constants are also placed here.
2. Each static object tree is connected interprocedurally to every formal-in node that represents that class.